Aluminum alloy fastening member and method for producing aluminum alloy fastening member

Abstract

Provided is an aluminum alloy fastening member including a chemical conversion coating having a novel composition as a colored coating, and a method for producing the aluminum alloy fastening member. The aluminum alloy fastening member includes a chemical conversion coating containing tellurium as a component element.

The invention claimed is: 
     
       1. An aluminum alloy fastening member comprising:
 a chemical conversion coating, the chemical conversion coating containing tellurium as a component element, 
 wherein the chemical conversion coating of the aluminum alloy fastening member presents a gray color that satisfies color tone ranges of −5≤a*≤8; −3≤b*≤10; and 40≤L*≤75, in a CIELAB color space as defined in JIS Z 8781-4 (2013), and 
 wherein the chemical conversion coating comprises 10% by mass or more of tellurium and/or a tellurium compound. 
 
     
     
       2. The aluminum alloy fastening member according to  claim 1 , wherein the chemical conversion coating has an average thickness of from 0.01 μm to 1.00 μm. 
     
     
       3. The aluminum alloy fastening member according to  claim 1 , wherein an aluminum alloy of the aluminum alloy fastening member has a composition represented by a general formula: Al a Si b MG c , with each of a, b, and c being % by mass; symbol a being a balance; 0.1≤b≤1.5; 0.2≤c≤5.6; and which contains unavoidable impurities. 
     
     
       4. The aluminum alloy fastening member according to  claim 1 , wherein the aluminum alloy fastening member is an element for slide fasteners, a slider for slide fasteners, a stopper for slide fasteners, or a button. 
     
     
       5. A method for producing the aluminum alloy fastening member according to  claim 1 , the method comprising forming the chemical conversion coating containing tellurium as the component element by immersing the aluminum alloy fastening member in a metal surface treatment solution containing the tellurium or a tellurium compound or a salt thereof. 
     
     
       6. The method according to  claim 5 , wherein the tellurium or the tellurium compound or the salt thereof is tellurium monoxide, tellurium dioxide, tellurium trioxide, tellurous acid, telluric acid, tellurium tetrachloride, dimethyl telluride, or a salt thereof, or a combination thereof.